Magma storage and evolution of the most recent effusive and explosive eruptions from Yellowstone Caldera
Magma storage and evolution of the most recent effusive and explosive eruptions from Yellowstone Caldera
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DOI：
10.1007/s00410-016-1244-x
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发表时间：
2016-04-01
影响因子：
3.5
通讯作者：
Gardner, James E.
中科院分区：
文献类型：
--
作者：
Befus, Kenneth S.;Gardner, James E.
在70至175年前，超过350公里(3)的高硅流纹岩岩浆从黄石火山口内喷涌而出。所有研究的熔岩和凝灰岩中的斑晶在晶体、喷发和破火山口尺度上都具有显著的同质性，并且产生750 +/- 25℃的QUILF温度，相平衡实验复制了在这些温度下观察到的斑晶组合，并表明岩浆都储存在上地壳中。石英玻璃包裹体含有1.0- 2.5%的H2O和50- 600ppm的CO2，但有些单位CO2含量相对丰富（300- 600ppm），有些单位CO2含量较低（50- 200ppm）。富含二氧化碳的岩浆被储存在90-150 MPa的温度下，含有60-75 mol%的二氧化碳。低co2岩浆在50-70 MPa的环境下储存，流体中含有丰富的h2o （X-CO2 = 40- 60%）。储存压力和挥发物与喷发年龄、体积或喷发方式无关。玻璃包裹体和基质玻璃中的微量元素含量保持了晶体分选产生的系统演化，估计范围为36 +/- 12至52 +/- 12 wt%。因为喷发的产物含有
Between 70 and 175 ka, over 350 km(3) of high-silica rhyolite magma erupted both effusively and explosively from within the Yellowstone Caldera. Phenocrysts in all studied lavas and tuffs are remarkably homogenous at the crystal, eruption, and caldera-scale, and yield QUILF temperatures of 750 +/- 25 degrees C. Phase equilibrium experiments replicate the observed phenocryst assemblage at those temperatures and suggest that the magmas were all stored in the upper crust. Quartz-hosted glass inclusions contain 1.0-2.5 % H2O and 50-600 ppm CO2, but some units are relatively rich in CO2 (300-600 ppm) and some are CO2-poor (50-200 ppm). The CO2-rich magmas were stored at 90-150 MPa and contained a fluid that was 60-75 mol% CO2. CO2-poor magmas were stored at 50-70 MPa, with a more H2O-rich fluid (X-CO2 = 40-60 %). Storage pressures and volatiles do not correlate with eruption age, volume, or style. Trace-element contents in glass inclusions and host matrix glass preserve a systematic evolution produced by crystal fractionation, estimated to range from 36 +/- 12 to 52 +/- 12 wt%. Because the erupted products contain